The complications of long-term corticosteroid therapy were reviewed in 100 elderly patients who were treated for chronic obstructive airways disease (n = 76), rheumatoid arthritis (n = 19) and ulcerative colitis (n = 5). The incidence of side effects was high (40%) and appeared to be dose-related. Osteoporosis (16%) and hypertension (12%) were the most common. Hypokalaemia occurred infrequently despite the fact that 69 patients were also prescribed diuretics. A further group of 36 patients receiving corticosteroids for polymyalgia rheumatica and giant cell arteritis also seemed to demonstrate a dose-related effect on the incidence of complications although this could not be confirmed statistically.